Beraprost (the general name of (.+-.)-1R*, 2R*, 3aS*, 8bS*)-2,3,3a,8b-tetrahydro-2-hydroxy-1-[(E)-(3S* )-3-hydroxy-4-methyl-1-octene-6-ynyl)-1H-cyclopentane[b]benzofuran-5-butyr ic acid) is a stable derivative of prostaglandin I.sub.2 (PGI.sub.2) and has a wide variety of physiological actions such as strong antithrombotic activity and peripheral vasodilator action. Thus, beraprost has been attracting attention as a drug for improving peripheral circulatory disturbance.
However, application of beraprost to ophthalmic preparations has not been started. Research and development of application of beraprost to therapeutic agents of ophthalmic diseases, especially glaucoma, cataract and the like, is waited for.